edmidor
6th Kyu
join:2008-05-19
Montreal, QC
| [Equipment] Strange intermitent problem
So far I could resolve all problems I encountered with my PAP2T based setups. All but one. Lately I noticed this intermittent problem: dialing from my normally working ATA - everything is OK. Dialing again - oops! - one way audio! And the weird part is that one time I can't hear the other party, and the other time I can, but the other party can't. Next time everything is OK again.
If the one way audio problem was permanent I knew what to check. But when most of the time it works OK, but every once in a while it fails - I can't think what goes wrong there. |
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Test99
Premium
join:2003-04-24
San Jose, CA
 ·DSL EXTREME
 ·InPhonex
| I wonder if there might be some problem with the router not maintaining the session between the ATA and the SIP server or the PSTN gateway correctly, causing ports to be blocked.
Do you experience this problem when you put the ATA directly on the Internet, with no router in the path, or when you put the ATA in the router's DMZ? |
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edmidor
6th Kyu
join:2008-05-19
Montreal, QC
1 edit | DMZ makes ATA outside of firewall, but not NAT. That appears to me NAT timing problem.
Any idea what to tweak on ATA or router?
I use VIA, not STUN, and registration timeout is 120s
Again, the weird thing that I generally can call, but sometimes I do have one-way audio...
ATA: PAP2T
Router: WRT54GL with Tomato |
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voipMatt
join:2008-07-30
Birmingham, AL
1 edit | reply to edmidor
Get some packet captures and look for the RTP streams.
That way you can see if they are both ways. |
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Test99
Premium
join:2003-04-24
San Jose, CA
·DSL EXTREME
·InPhonex
| reply to edmidor
said by edmidor  :DMZ makes ATA outside of firewall, but not NAT. That appears to me NAT timing problem. Put the ATA directly on the Internet, taking the router out of the picture entirely. If the problem goes away, it must involve the router. If the problem does not go away, then it is unrelated to the router.
Matt's suggestion involves more work, but should tell you a lot about what is happening. You can download WireShark here. |
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edmidor
6th Kyu
join:2008-05-19
Montreal, QC | I'll try. The problem is that I can't say whether problem has gone or not for intermittent problem. I can make 5 successful calls and decide it's fixed, and then 6th call fails again. |
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Test99
Premium
join:2003-04-24
San Jose, CA | Understood. Intermittent problems are the hardest to resolve. |
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edmidor
6th Kyu
join:2008-05-19
Montreal, QC | reply to voipMatt
Is there any guide or anything explaining how to perform VoIP traffic capture with WireShark? |
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Test99
Premium
join:2003-04-24
San Jose, CA
·DSL EXTREME
·InPhonex
| The WireShark users' guide is here.
For a quick start:
- Download and install the program.
- Make sure the ATA and the computer running WireShark are both connected to an Ethernet hub (not a switch) so the computer can see the ATA's packets.
- From the WireShark menu bar, select Capture/Interfaces.
- On the line that lists your Ethernet adapter, click Start. |
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